1. Field of Invention
This invention relates to the sport of golf, specifically to a device that allows one to practice his or her golf swing using a relatively small area.
2. Description of Prior Art
Golfers commonly practice their golf swing at driving ranges, where the effectiveness of each swing is judged by the flight of a golf ball. Thus, a large field (several hundred yards long) is required.
By having a practice device that occupies a relatively small area (5-10 feet long), golfers can enjoy practicing their swing almost anywhere: office, home, backyard, etc. Thus inventors have created several types of practice devices for this purpose.
These prior inventions can be categorized by how the restricted ball movement is defined, as follows:
(a) tethered ball using a rigid cord; PA1 (b) tethered ball using a flexible cord; PA1 (c) translating ball along a guided track.
U.S. Pat. No. 4,861,035 to Page (1988) offers a device employing a tethered ball with a rigid cord. This does not provide the proper feel for the game, since the ball is not allowed to freely translate forward. Furthermore, this type of device usually consists of many components that prohibit the clear view of the ball desired by golfers for focussing on the ball.
In category (b), U.S. Pat. No. 3,830,504 to Koo (1974), there are further complications as using a flexible cord presents the danger of the tether breaking if a large force is applied when striking the ball. To account for this, a simulated practice golf ball which is substantially lighter than a standard golf ball is employed, as proposed in U.S. Pat. No. 4,071,250 to Vroome (1976) and U.S. Pat. No. 4,655,460 to Hambright (1986). The problem of using a lighter practice ball is that one can no longer sense the true feeling of the game because a lighter ball reacts differently upon impact than a standard golf ball. Furthermore, the effectiveness of a golf swing is difficult to determine when a standard golf ball is not employed.
U.S. Pat. No. 2,929,632 to Moffatt (1957) and U.S. Pat. No. 4,932,660 to Wang (1989) disclose practice devices that allow visual determination of a straight, hooked or sliced ball based on the nature of a tethered ball rotating about a horizontal axis.
Our invention falls into category (c), that of translating a golf ball along a guided track. This approach allows one to employ an actual golf ball while eliminating the problem of having an excessive strain on string tension of the above tethering approaches. In addition, our invention differs from previous inventions in this category as follows:
(a) A golf ball is translated along a rope by creating a passage inside the golf ball for the rope to pass through, and not by an external ring connected to the ball as is used, for example in U.S. Pat. No. 3,754,761 to Pruss (1972) and U.S. Pat. No. 4,139,197 to Windall (1978). This approach eliminates the possibility of the ball being dislodged from its external connection after a repeated period of bombardments by a golf club.
(b) The guided rope enters and exits the golf ball at an angle. This allows the backside of the golf ball to be clear of any obstruction and provides optimal contact with a golf club.
Although U.S. Pat. No. 3,558,134 to Hoitsma (1968) discloses the technique of sliding a diametrically apertured ball along a guide wire, our approach of running a rope through an angular passage inside a solid-core ball is systematically different and more suitable for golf practice devices. This is because by angling the placement of the rope, a clear point of contact (i.e. hitting point) becomes available that does not exist in U.S. Pat. No. 3,558,134 to Hoitsma (1968).